The resource of ultra-thick coal layers (8-20 m) under constructions, railroads, and water bodies is widely distributed in China, and these coal layers are important coal layers for improving exploitation efficiency and yield in coal mines in China. At present, there are mainly two types of exploitation methods for ultra-thick coal layers (8-20 m) under constructions, railroads, and water bodies in China: the first type includes layered mining, caving mining, and thickness-limit mining, etc., which utilizes a spontaneous caving approach to manage coal roofs, and have the following problems: spontaneous roof caving may cause surface subsidence and damages to surface constructions and railroads, etc., and may result in settlement of ground water level and damage to the ecologic environment; the second type includes strip mining, large area coordinated mining, reducing subsidence by grouting mining, etc., though these mining methods have some surface subsidence control effects and can ensure safe use of surface constructions and railroads, they have disadvantages such as low level of mechanization, low recovery ratio, high production cost, low production efficiency, small scale or partially in research. Hence, it is urgent to develop a coal mining method that can effectively control strata movement, ensure safe use of surface constructions and railroads, etc., and efficiently recover ultra-thick coal layers (8-20 m) under constructions, railroads, and water bodies.